Image file for storing digital images and ancillary data values using multiple encoding methods

ABSTRACT

An image format for storing digital images within a baseline DCT compatible bitstream comprises entropy coded image data, a first application marker storing a first data value using a first encoding method to convey a first information value related to the image, and a second application marker storing a second data value using a second encoding method to convey the same said first information value related to the image. More specifically, the first application marker uses TIFF tags within an Exif application marker and the second application marker uses a FlashPix compatible structured storage stream, while the entropy coded data includes restart markers to define tile boundaries within the entropy coded image data.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of application Ser. No. 09/950,199, filed Sep.10, 2001 which is a continuation of U.S. application Ser. No.09/028,682, now U.S. Pat. No. 6,310,647 issued Oct. 30, 2001.

FIELD OF THE INVENTION

The invention relates generally to the field of digital photography, andin particular to image file formats developed for use with digitalcameras and their applications.

BACKGROUND OF THE INVENTION

Electronic still cameras typically capture, digitize, and store imageson a removable memory device, such as a PCMCIA or Compact Flash card.The images are stored on the card in separate image files. Manydifferent image file formats may be used. To increase the number ofimages stored per card, image compression is typically used to reducethe file size. The most popular compression standard is the JPEG (JointPhotographic Expert Group) baseline DCT (discrete cosine transform)method, which compresses the image components (for example a luminancecomponent Y and two color difference components Cb and Cr) using 8×8pixel blocks.

It is desirable for digital cameras to produce images that can be easilytransferred into other digital devices (e.g. computers) for editing,display, transmission, archival storage, and printing. This requires astandard image data format, not just standards for the physical andelectrical compatibility of the removable memory card. The format shouldbe supported by popular application software, so that the user does notneed to worry about whether the image format is compatible with thevarious image-capable applications on their computer.

The “FlashPix” image format (defined in FlashPix Format Specification,version 1.0, (Eastman Kodak Company, Sep. 11, 1996)) has been developedto serve as both an “interchange” format between devices (e.g. cameras)and applications (e.g. computer picture editing packages), and as a“native” format for image editing that allows the images to be easilyand rapidly edited. This is accomplished using a hierarchical, tiledimage representation within a “structured storage” file. A FlashPix filecontains the complete image plus a hierarchy of several lower-resolutioncopies within the same file. Images at each resolution also are dividedinto rectangular tiles (e.g., squares), which enable the application tominimize the amount of image data processed to access, display or printa portion of the scene content. FlashPix allows optional “ancillary”data to be stored in the same structured storage file, along with theimage data. This ancillary data can include digital audio recordings andparameters such as the time and date the photo was taken, the camerazoom position and focus distance, the scene illumination level, cameracalibration data, image copyright owner, etc. For further informationabout the FlashPix image format see the aforementioned FlashPix FormatSpecification, version 1.0, (Eastman Kodak Company, Sep. 11, 1996),which is available from Eastman Kodak Co. or at the Eastman Kodak Co.Web site at www.kodak.com/go/flashpix, and is incorporated herein byreference.

Unfortunately, because FlashPix is a relatively new format, manycomputer applications are not yet capable of reading FlashPix imagefiles. On the other hand, most applications are able to open imagesstored in “JPEG interchange format” (JIF) files defined by the BaselineDCT (JPEG) version of ISO/IEC 10918-1, which is incorporated herein byreference. This standard allows “application markers” to be included inthe JIF bitstream. The data inside an application marker is ignored byapplications that are not familiar with the marker. A number of imagefile formats have been developed which use a single application markersegment to store ancillary data and a reduced-resolution “thumbnail”image. These image formats include JFIF, defined in “JPEG FileInterchange Format Version 1.02 Sep. 1, 1992 C-Cube Microsystems”, theJPEG compressed version of Exif (Exchangeable image format) described in“Digital Still Camera Image File Format Proposal (Exif) Version 1.0 Mar.24, 1995 JEIDA/Electronic Still Camera Working Group” and SPIFF, definedin “ITU-T Rec. T.84, Annex F—Still Picture Interchange File Format,1995”, which are each incorporated herein by reference.

For example, Exif allows some camera-related ancillary data, such as thedate and time, lens f/number, etc, to be recorded using TIFF (Tag imagefile format) tags within an application marker 1 (APP 1) segment in theJIF bitstream. (TIFF is defined in the TIFF Revision 6.0, Jun. 3, 1992,by Adobe Corp. and available on the Web at http://www.Adobe.com, andincorporated herein by reference.) Exif images can be opened by anycomputer application software that incorporates a JPEG reader. However,the ancillary data in the Exif file can only be accessed by applicationsdesigned specifically for Exif. When an Exif file is converted to aFlashPix file (e.g. by the Microsoft PictureIt application), theinformation recorded using the TIFF tags is typically ignored by thereader, since the FlashPix conversion programs are typically notfamiliar with the structure of the Exif application marker and thereforeignore it. Thus, the ancillary information is lost. If the FlashPixapplication was familiar with the Exif application marker, it would needto read each individual TIFF tag, decode the information values fromeach tag (for example, one specific tag encodes the camera f/number as arational number value) and then re-encode the values using the encodingmethod specified by FlashPix (which encodes the camera f/number as areal number value, rather than a rational number value, for example)Each resolution level of a FlashPix image is “tiled” into 64×64 pixelimages, and stored as a group, or “stream” of these small imagesections.

However, the baseline DCT JPEG standard does not allow the image data tobe stored in tiles. Instead, the data is stored as a single imagerecord, by encoding all of the image blocks from left to right and topto bottom into a single data record. Therefore, to convert an Exif orother JIF compatible file format to a FlashPix image, the fullresolution image is normally decompressed, tiled, and then recompressed.This process takes time, and may add compression artifacts.

What is needed is an image file format that is completely compatiblewith the Baseline DCT (JPEG) version of ISO/IEC 10918-1, so that it canbe opened by all existing “JPEG” enabled software applications, yet canbe quickly and easily converted to the FlashPix format, so that newapplications can take advantage of the tiling and ancillary informationcapabilities offered by FlashPix.

SUMMARY OF THE INVENTION

The present invention is directed to overcoming one or more of theproblems set forth above. Briefly summarized, according to one aspect ofthe present invention, there is provided a single digital image file,comprising:

a) entropy coded image data provided by processing a digital imagecaptured by a digital camera;

b) a first ancillary data value using a first encoding method to conveya first information value related to the digital image captured by thedigital camera; and

c) a second ancillary data value, different from said first ancillarydata value and encoded using a second encoding method, different fromsaid first encoding method, wherein the second ancillary data valueconveys the same said first information value.

Another aspect of the present invention is to provide a memory forstoring digital image files, comprising:

a) a plurality of digital image files, and

b) a directory that indicates where the data for each of the pluralityof digital image files is stored on the memory card, wherein each of theplurality of digital image files comprises:

-   -   i) entropy coded image data;    -   ii) a first ancillary data value using a first encoding method        to convey a first information value related to the digital image        captured by the digital camera; and    -   iii) a second ancillary data value, different from said first        ancillary data value and encoded using a second encoding method,        different from said first encoding method, wherein the second        ancillary data value conveys the same said first information        value.

These and other aspects, objects, features and advantages of the presentinvention will be more clearly understood and appreciated from a reviewof the following detailed description of the preferred embodiments andappended claims, and by reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a digital imaging system including adigital camera that generates a multi-format compatible image fileformat according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Because imaging systems and formats are well known, the presentdescription will be directed in particular to elements forming part of,or cooperating more directly with, systems and formats in accordancewith the present invention. Elements not specifically shown or describedherein may be selected from those known in the art. Many aspects of thepresent description may be implemented in software. Unless otherwisespecified, all software implementation is conventional and within theordinary skill in the programming arts.

The invention is an image file format developed to be compatible with oreasily transcodable to multiple image formats. The format follows theBaseline DCT (“JPEG”) version of ISO/IEC 10918-1, so that it can beopened by existing “JPEG” enabled software applications such asMicrosoft Word for Windows, Adobe Photoshop, etc. In addition, it caninclude application markers for both Exif and SPIFF, two different JPEGinterchange format (JIF) based image formats. Furthermore, it includesfeatures that allow easy transcoding to the FlashPix image format, suchas: (1) an application marker segment that includes the “Image InfoProperty Set” defined in the FlashPix standard, so that this data can becopied into the FlashPix file. (2) restart markers that define 64×64tile segments added to the entropy coded image, so that the entropycoded Baseline DCT full size image can be converted into the proper sizetiles required by the FlashPix image format without decompression.

A system block diagram according to the invention is shown in FIG. 1 ofa digital still camera 10 and respective first and second host computers12 and 14. Images are captured through a lens 16 by a CCD sensor 18,converted to digital image data by an A/D converter 20, processed by aprogrammable processor 22, and stored on a removable memory card 24 viaan interface 26. The card 24 stores a single file 40 for each digitalimage (image #1, image #2, . . . image #N) and a directory 42 thatindicates how many image files 40 exist on the card 24, and where thedata for each file is located. The memory card 24 can then be removedfrom the camera and inserted into card readers 50 in the host computers12 and 14 where an image can be edited, displayed, printed, transmitted,etc using various software applications. Some of these computerapplications, e.g., the host computer 12, may be capable of readingFlashPix and JIF files, while others, e.g., the host computer 14, may becapable of only reading JIF files.

Each of the image files 40 is organized as shown in TABLE 1. The SOI,DQT, DHT, SOF, SOS, and EOI markers, which are all well known since theyare defined in ISO/IEC 10918-1, comprise the following: TABLE 1 ImageFile SOI (Start of Image) APP8 segment (SPIFF fixed data) APP 1 segment(Exif TIFF tags, plus additional TIFF/EP tags, Kodak cameraInfo tags andTIFF thumbnail) APP2 segments (FlashPix standard image data area andImage Info Property Set) DQT (Quantization Table) DHT (Huffman Table)SOF (Start of Frame) SOS (Start of Scan) Entropy Coded Data Y, Cb, Cr4:1:1 data derived from sRGB EOI (End of Image)1. SOI (Start of Image) is the marker code “FFD8” which defines thebeginning of the file.

2. The SPIFF marker is defined in the reference cited earlier. Theformat of this marker segment is shown in Table 2. TABLE 2 SPIFFapplication marker Type Parameter and size Value MN (magic number) I.32X’FFD8FFE8(includes SOI) HLEN (header length) I.16 28 (Not including MN)IDENT (SPIFF identifier) I.32 X‘53504600’ VERS (Version) I.16 X‘0100’ P(Profile) I.8 X‘01’ (Continuous tone) C (Compression type) I.8 X‘05’(JPEG continuous tone) S (Color space) I.8 X‘03’ (JFIF color) R(Resolution units) I.8 X‘01’ (dots per inch) HEIGHT I.32 Lines in lumainput image WIDTH I.32 Pixels per line in luma input image VRES I.32 72dots HRES I.32 72 dots3. The Exif marker is defined in the reference cited earlier. The formatof this marker segment is shown in Table 3.4. The FlashPix Image Info Property Set marker is defined later in thisdocument.5. DQT (Define Quantization Table) is a marker code segment that beginswith “FFD9” which defines the beginning of the quantization tables usedfor JPEG compression. Three kinds of tables are included, one forluminance (Y) and one for each of the two color difference signals Cband Cr.6. DHT (Define Huffman Table) is a marker code segment that begins with“FFC4” which defines the Huffman Tables used for JPEG compression.Within the DHT, four sets of parameters are recorded. These are the DCand AC tables for Y and C, respectively.7. SOF (Start of Frame) is a marker code segment that begins with“FFCO”. It provides the following parameter information:

Indicates baseline JPEG compression is used

Sample precision in bits

Number of vertical lines in the Y image

Number of horizontal pixels in the Y image

Three components (Y, Cr, Cb)

Cr and Cb subsampling (Cr and Cb have ½ as many lines and pixels perline as Y)

Which quantization table is used for Y, Cb, and Cr. TABLE 3 Exifapplication marker APP1 Marker = 0x FEE APP1 Length Exif Identifier &Pad TIFF Header IFD 0 describing JPEG Compressed Image Number ofdirectory entries ImageDescription Make, etc. ExifIFD Tag/Pointer NextIFD Offset Exif Private IFD Number of directory entries Exif VersionDateTimeOriginal etc Next IFD Offset IFD 1 describing Thumbnail ImageImage Width Image Length BitsPerSample CompressionPhotometricInterpretation StripOffsets SamplesPerPixel RowsPerStripStripByteCounts XResolution YResolution Resolution Unit Next IFD OffsetThumbnail Image data (1 strip RGB image data)8. SOS (Start of Scan) is a marker code segment that begins with “FFDA”.It provides the following parameter information:

Indicates that there are three components in the scan

Indicates which Huffman tables are used for Y, Cb, and Cr.

9. The Entropy Coded Data is tiled as shown in Table 5. Each 64×64 pixel(4096 pixel) tile includes an 8×8 group (64 total) of luminance DCTblocks and 4×4 group (16 total) Cb and Cr chroma DCT blocks. Eachmacroblock consists of 4 luminance and 1 each Cb and Cr chrominanceblocks. Therefore, restart markers are placed after appropriate groupsof macroblocks.

10. EOI (End of Image) is the marker code “FFD9” which defines the endof the file.

FPXR Application Segments

All FPXR (FlashPix ready) application segments have a similar structure.This structure is depicted in Table 4. It consists of a 2-byte APP2marker followed by a 2-byte segment length (L) value stored in bigendian format. The initial 4 bytes follow the application markerspecification in ISO/IEC 10918-1. Following this is 5 bytes consistingof a NULL-terminated string “FPXR.” The next byte is a version number.The next byte is a type followed by a series of L-9 bytes whose formatdepends on this type. Bytes 0 through 10 are referred to as the FPXRsegment header. TABLE 4 FPXR Application Segment.

Note that the segment length, L, is a 16-bit number. Therefore, themaximum size allowed in any one FPXR data area is 65526 bytes.

The valid values for FPXR types are: Value Description of FPXR Data AreaRequired/Optional 0x00 Standard Image Data required 0x01 Contents Listoptional 0x02 Stream data optionalThe exact format of the various FPXR data areas will be described in thefollowing sections.FPXR Standard Image Data Area

Each image file contains (as the first FPXR APP2 segment) a single FPXRstandard image data segment (FPXR type 0×00). In some cases, a digitalcamera could create an image file which has no other FlashPix specificdata. This single segment serves to establish that the file includesrestart markers that define the tile boundaries, as described later. Theformat of the standard image data area is defined in Table 5. Eventhough these values are embedded in the JPEG stream, they are repeatedhere for the convenience of the application reading the FPXR file. TABLE5 FPXR Standard Image Data Area. Offset Value Description 11 Pixel Xdimension 12 (# pixels per line) 13 Pixel Y dimension 14 (# lines) 15Color space 16 Chroma subsampling 17 18 Offset to start 19 of JPEG DQTheader 20 21 22 Offset to start 23 of JPEG SOF header 24 25 26 Offset tostart of JPEG 27 compressed data 28

The valid values for color space are: Value Description 0x03 NIFRGB 0x01Monochrome

These values are consistent with their definitions in the FlashPixspecification. The chroma subsampling value is stored exactly as in thetile header table of the Subimage Header Stream of the FlashPix file.The valid values are: Value Horizontal Subsampling Ratio VerticalSubsampling Ratio 0x11 1 1 0x21 2 1 0x22 2 2

In the case of monochrome, the subsampling value is not meaningful andis set to zero.

In addition, there are three file offsets (measured in bytes from thebeginning of the FPXR file) to aid the application in putting togetherpieces of the FPXR file to form the abbreviated JPEG header table in theCompression Description Group of the Image Contents Property Set of theFlashPix file and also to build tile headers. Each of these offsets arestored in 32-bit unsigned integer (big endian). The first offset is theaddress of the first byte of the DQT header in the FPXR file. The secondoffset is the address of the first byte of the SOF header in the file.The last offset is the address of the first byte of the actualcompressed data (i.e., following the SOS segment).

FPXR Contents List Data Area

The image file may also include an FPXR contents list segment (FPXR type0×01). This segment contains a list of streams that are to be added tothe FlashPix image object created from the JIF file. Since propertysets, such as the FlashPix Image Information Property Set, are specialcases of streams, they are easily handled via this mechanism.

The format of the FPXR contents list data area is defined in Table 6below. TABLE 6 FPXR Contents List Data Area. Offset Value Description 11Number of entries 12 =N 13 Name/size pairs - one pair for each entry

The number of entries, N, is a 16-bit unsigned integer in big endianformat defining how many streams are to be added to the FlashPix imageobject. For each of these entries, a pair is provided giving the name ofthe stream to create and the size (in bytes) of the stream data. Thesepairs are packed tightly in the bytes of the file starting at offset 13in the FPXR segment. Each pair has an associated index number (0, 1, . .. , N−1) that is implicitly derived from its position in the array ofpairs.

The first member of each name/size pair is a WCHAR (16-bit percharacter, null-terminated string in the Unicode code page) containingthe name of the FlashPix stream to create. The stream includes acomplete pathname specification relative to the FlashPix image objectstorage, for example “\005SummaryInformation. The second member of eachname/size pair specifies the size (in bytes) of the stream that is beingcreated.

FPXR Stream Data Area

For every entry in the FPXR contents list segment, there are 1 or moreFPXR stream data segments that define the contents of the streams to becreated. Since APPn segments are limited to a size of 64K bytes each, itis possible that stream data might be split across multiple FPXRsegments (e.g., an audio extension). Therefore, the FPXR stream datasegment provides a mechanism for such splitting.

The format of the FPXR stream data area is defined in Table 7 below.TABLE 7 FPXR Stream Data Area. Offset Value Description 11 Index incontents 12 list 13 14 Offset to start 15 of data in full FlashPix 16stream 17 Stream data

The first entry is a 16-bit unsigned integer that specifies the indexnumber from the contents list that this stream data corresponds to. Thesecond entry is a 32-bit unsigned integer that specifies the offset(measured in bytes, relative to zero) into the full FlashPix streamwhere the following data belongs. The size of the stream data in aparticular FPXR stream data area is L-15 bytes (where L was defined asin Table 5). In the most simple case, a stream fits completely in oneFPXR segment, and the offset value would be zero. In other cases, thestream data is separated across multiple FPXR segments all of which havethe same “index” number (and each having different offset numbers).

Creating Property Sets

The binary format for property sets is contained in section A.2 of theaforementioned FlashPix Specification. To include this informationwithin a JIF compatible file, the FPXR stream data area of theapplication segment (i.e., starting at byte 17 in the segment) containsthe binary content of a property set. A property set consists of aProperty Set Header followed by a Property Set Format ID/Offset Pairfollowed by the one and only one Property Set Section containing theactual properties. The Property Set Header is a fixed size array (28bytes) containing constants values (per property set). The FormatID/Offset Pair is a fixed size array (20 bytes) also containing constantvalues (per property set). Therefore, the only variable portion is thatof the section.

The format of a Property Set Section follows the conventions of AppendixA of the FlashPix Specification. A section consists of a Section Header,followed by an array of Property ID/Offset Pairs, followed by an arrayof Property Type/Value pairs. The section header contains two DWORDs(i.e., 32-bit integer values). The first DWORD is the size of thesection (in bytes). The second DWORD is the count of properties, m,contained in the section.

Immediately following the header is an array of m pairs. Each pairconsists of two DWORDs. The first DWORD in a pair contains a Property ID(PID). The second DWORD contains the offset within the section to thefirst byte of the type/value pair for the property with the PIDspecified in the first DWORD. These offsets are measured in bytes fromthe start of a section to the start of the type/value pair. This meansthat the offsets can be copied directly from the FPXR applicationsegment into a structured storage file property set without anyrecalculation of offsets. This array of pairs is not required to besorted in any particular order (i.e., the PIDs are in any order chosenby the writer). The PIDs that are allowed to be contained in the arrayare those defined by the corresponding property sets in the FlashPixformat.

Immediately following the PID/offset array is a “list” of m pairs. Eachpair consists of a DWORD type indicator and the value for a particularproperty. The value is variable size in length as dictated by the typeindicator. All type/value pairs begin on a 32-bit boundary in thesection. The possible types are given in Table 8 below. TABLE 8 PropertyTypes Type Name Type Value VT_I2  2 VT_I4  3 VT_R4  4 VT_R8  5 VT_DATE 7 VT_BOOL 11 VT_VARIANT 12 VT_I1 16 VT_UI1 17 VT_UI2 18 VT_UI4 19 VT_I820 VT_UI8 21 VT_INT 22 VT_UINT 23 VT_LPSTR 30 VT_LPWSTR 31 VT_FILETIME64 VT_BLOB 65 VT_CF 71 VT_CLSID 72 VT_VECTOR 0x1000 VT_ARRAY 0x2000

The data formats corresponding to each of the property types arecontained in section A.2.3 of the FlashPix Specification.

JPEG Restart Markers

The compressed image data in the JPEG stream must contain restartmarkers (RST) at the beginning of every JPEG block that begins a new64-pixel boundary. The number of minimal coding units (MCUs) that thiscorresponds to varies depending on the chroma subsampling and componentinterleaving methods being applied.

An MCU block is comprised of the total number of MCUs necessary toencode all supplied components according to their sampling factor andinterleaving method. All components are interleaved in FPXR files.

In the case of chroma subsampling value 0×11 (horizontal and verticalsubsampling ratios of 1), there are 3 MCUs per each 8×8-pixel block (nosubsampling therefore no reconstruction). Therefore, the RST markersoccur every 8 MCU blocks (24 MCUs).

For a chroma subsampling value of 0×22 (H/V ratios of 2), there are 6MCUs per each 16×16 pixel block (after reconstruction is performed).Therefore, the RST markers occur every 4 MCU blocks (24 MCUs).

For a chroma subsampling value of 0×2 1 (Horizontal subsampling ratio of2, vertical of 1), there are 4 MCUs per each 16×8 pixel block (afterreconstruction is performed). Therefore, the RST markers occur every 4MCU blocks (16 MCUs).

The locations specified above for RST markers are the only ones includedin a file containing the FPXR application marker. In other words, areader application that senses that a JIF file is in fact an FPXR filecan safely assume that the only RST markers that will be encountered inthe JPEG stream are those that are placed according to the above rulesto facilitate the tiling of the FlashPix data.

The invention has been described with reference to a preferredembodiment. However, it will be appreciated that variations andmodifications can be effected by a person of ordinary skill in the artwithout departing from the scope of the invention.

PARTS LIST

-   10 digital still camera-   12 first host computer-   14 second host computer-   16 lens-   18 CCD sensor-   20 A/D converter-   22 programmable processor-   24 removable memory card-   26 interface-   28 image memory-   30 color LCD display-   32 user button-   40 file-   42 directory-   50 card reader

1. A single digital image file, comprising: a) entropy coded image dataprovided by processing a digital image captured by a digital camera; b)a first ancillary data value using a first encoding method to convey afirst information value related to the digital image captured by thedigital camera; and c) a second ancillary data value, different fromsaid first ancillary data value and encoded using a second encodingmethod, different from said first encoding method, wherein the secondancillary data value conveys the same said first information value.
 2. Asingle digital image file as claimed in claim 1 wherein the first datavalue is encoded using a TIFF tag, and the second data value is encodedusing a second encoding method other than TIFF tags.
 3. A single digitalimage file as claimed in claim 1 wherein the entropy coded image data isdiscrete cosine transform compressed data.
 4. A single digital imagefile as claimed in claim 1 wherein the first data value is encoded usinga TIFF tag, and the second data value is encoded using a second encodingmethod other than TIFF tags.
 5. A single digital image file as claimedin claim 1 wherein the first information value provides an image capturedate of the digital image captured by the digital camera.
 6. A singledigital image file as claimed in claim 1 wherein the first informationvalue provides a camera parameter.
 7. A single digital image file asclaimed in claim 1 wherein the first information value provides a cameralens zoom position.
 8. A single digital image file as claimed in claim 1wherein the first information value provides a camera lens focusdistance.
 9. A single digital image file as claimed in claim 1 whereinthe first information value provides an image copyright owner of thedigital image captured by the digital camera.
 10. A single digital imagefile as claimed in claim 1 wherein the first information value providesa description of the digital image captured by the digital camera.
 11. Amemory for storing digital image files, comprising: a) a plurality ofdigital image files, and b) a directory that indicates where the datafor each of the plurality of digital image files is stored on the memorycard, wherein each of the plurality of digital image files comprises: i)entropy coded image data; ii) a first ancillary data value using a firstencoding method to convey a first information value related to thedigital image captured by the digital camera; and iii) a secondancillary data value, different from said first ancillary data value andencoded using a second encoding method, different from said firstencoding method, wherein the second ancillary data value conveys thesame said first information value.
 12. A memory card claimed in claim11, wherein the first data value is encoded using a TIFF tag, and thesecond data value is encoded using a second encoding method other thanTIFF tags.
 13. A memory as claimed in claim 11, wherein the entropycoded image data is discrete cosine transform compressed data.
 14. Amemory as claimed in claim 11, wherein the first data value is encodedusing a TIFF tag, and the second data value is encoded using a secondencoding method other than TIFF tags.
 15. A memory card claimed in claim11, wherein the first information value provides an image capture dateof the digital image captured by the digital camera.
 16. A memory asclaimed in claim 11, wherein the first information value provides acamera parameter.
 17. A memory as claimed in claim 11, wherein the firstinformation value provides an image copyright owner of the digital imagecaptured by the digital camera.
 18. A memory as claimed in claim 11,wherein the first information value provides a description of thedigital image captured by the digital camera.
 19. A memory as claimed inclaim 11, wherein the memory is a removable memory card.